We don’t often associate news in Science Today with the game of poker, however a study published in the magazine states that scientists have developed a computer program that is simply unbeatable when playing fixed limit two player Texas Hold’em. The program, called Cepheus, plays such a perfect game that Michael Bowling, co-author of the University of Alberta study states that, "We’re not saying that it’s guaranteed to win money on every single hand, what we’re saying is that, in the long run, if you looked at all the hands that could happen and you averaged all of those, then the computer can’t be losing, at a losing rate, it has to be either breaking even or winning."
Developing a program to win at Texas Hold’em is extremely difficult due to the fact that you cannot give the program all of the information required, i.e you don’t know what cards are on the board, however Cepheus searches its vast database to find the very best move possible. Bowling explains that, "It does that by thinking of all possible decision points, and every possible action that could take place from those points,” adding that should it ever play randomly and lose money, then it equates how much it would have won with perfect play and adds the losses to what’s called a ‘regret’ value, updates its information and moves its strategy. After 70 days of training, calculating regret values and updating its information, Cepheus had reached perfect play, however the team working on the project have been thinking of the program for 11 years.
The next challenge for the team is to create a program that is unbeatable when playing heads up no limit Texas Hold’em, however that task they believe will be almost impossible, as would the development of a program for a three player game. Poker is in fact just the starting point for Cepheus and the developers believe that it could help doctors when treating diabetes by computing the optimal response when diet or activity levels change.